Wax

ABSTRACT

The invention relates to a novel wax and also to a process for preparing the wax which can be chemically modified in a simple, flexibly adaptable, inexpensive and environmentally friendly way. For this purpose, it is provided for the untreated waxes to be subjected to a low-temperature plasma treatment by means of which the waxes can be chemically modified in accordance with the application.

Waxes are known. For the purposes of the invention, waxes are organicmaterials which at about 20° C. are generally kneadable, solid tobrittle-hard, translucent, opaque and/or polishable and which areconverted above 40° C. into a relatively low-viscosity melt. Waxes can,for example lacuna! animal waxes, for example beeswax, plant waxes whichconsist predominantly of esters of higher fatty acids, for examplepalmitic acid, and higher alcohols, for example cetyl alcohol, myricylalcohol, naturally occurring mineral waxes, paraffin waxes (solidalkanes), polyolefin waxes, montan waxes (esters of montanic acid),further synthetic waxes, for example esters derived, for example, frompolyethylene, chlorinated hydrocarbons and others and other naturalwaxes, for example esters of higher monohydric alkanols and highermonobasic carboxylic acids.

It is known that these waxes can be used, for example, for coating andimpregnating various materials, for example paper, wood, leather, etc.,and for producing primarily aqueous, environmentally-friendly surfacecoating systems, for electrical insulation, etc. In a number of theseapplications, the waxes are processed in the form of dispersions,emulsions and solutions, so that the dispersibility, emulsifiability andsolubility of the waxes is a very important processing parameter.

Furthermore, waxes are used as auxiliaries in plastics processing or asstarting materials for producing surfactants, plasticizers, soaps anddetergents. Here, it is known that only special waxes can be used forcertain application areas among those mentioned by way of example, thesespecial waxes having to be prepared either by chemical modification ofthe waxes mentioned or by a complicated and therefore expensive specialsynthesis. A disadvantage here is that in the known processes for thechemical modification or special syntheses, different processes have tobe employed for the modification or synthesis depending on the type ofwax used and on the desired field of application. Thus, a separate planttechnology is necessary in each case for producing particular waxesdirected at a concrete application, and this makes the special waxesobtained considerably more expensive.

A further significant disadvantage of a number of the known modificationprocesses is that often toxic and/or aggressive starting materials, forexample SO₂ and Cl₂ in sulfochlorination, HNO₃ in nitration, arerequired and/or toxic and aggressive reaction products, for example HClin sulfochlorination, are formed. Thus, in addition to the complicatedproduction process, a comprehensive protective mechanism for protectingthe environment from the toxic and/or aggressive materials is necessary.

It is therefore an object of the invention to provide a wax which issimple and inexpensive to prepare and whose properties can be chemicallymodified in a simple, flexibly adaptable, inexpensive andenvironmentally friendly way.

According to the invention, this object is achieved by subjecting knownuntreated waxes to a low-temperature plasma treatment in a frequencyrange from preferably 10 kHz to 10 GHz. For the purposes of the presentinvention, low-temperature plasma treatment means that the material tobe treated is itself not heated above a certain temperature range, forexample from 40° to 60° C. It has surprisingly been found that the waxesthus treated have an increased wettability, an improved dispersibility,emulsifiability and solubility and also an improved reactivity toward awide variety of materials. This enables, on the one hand, the waxes ofthe invention to be used in the known fields of application without eachindividual application necessitating a specific modification to givespecial waxes or special syntheses directed only at this application.One and the same treatment of the waxes enables, merely by varying theprocess parameters during the low-temperature plasma treatment, thewaxes to be optimally matched to different fields of application, i.e.matched to the chemical properties required of the waxes for thesefields of application. In addition, the surprisingly simple possiblechemical modification of the waxes opens up completely new fields ofapplication, for example as dispersants for pigment concentrates, hotmelts for coating, melt adhesives or compatibilizers for compounds.

Particular preference is given to a wax into which are incorporated bymeans of the low-temperature plasma treatment, for example by selectionof of a composition of the process gas during the low-temperature plasmatreatment, where process gas is here an inert gas used, an inert gasmixture used, a reaction gas, a reaction gas mixture, to the untreatedwax, for example the type of the wax, a particle size, a particlesurface and the planned use of the treated product, into the waxes forthe respective application the required polar groups, for examplecarbonyl, hydroxyl, carboxyl and amino groups.

A particularly preferred wax is obtained when the low-temperature plasmatreatment of the untreated waxes is carried out using changingfrequencies, preferably using combinations of variously high, changingfrequencies. Here, simultaneous treatment with a reaction gas plasmaand/or a plasma of a reaction gas mixture enables very advantageoustailoring to a different chemical modification of the untreated waxeswith matching of the frequencies, the inert gas, the reaction gas, thestarting material and the desired use of the treated waxes being able tobe carried out optimally.

It has been found that the process found enables the proportion ofrequired polar groups to be decisively increased and combined, thusgiving a substantial, completely surprising step change in quality whenthe waxes treated according to the invention are used.

Further advantageous embodiments of the invention can be derived fromthe other features indicated in the subclaims.

The invention is illustrated below in an example with the aid of theassociated drawing which shows a flow diagram of a process procedure forpreparing a wax.

The FIGURE is intended to clarify the process with the aid of thediagram. In a first process step 10, the untreated waxes available asstarting materials are subjected to preprocessing. The untreated waxesare here, for example, brought into a powder and/or granule form, forexample a coarse powder form. As starting material, it is possible touse all known waxes of which some have been mentioned by way of examplein the introduction.

In a next process step 12, the prepared starting material is placed in aprocess chamber. The process chamber can here be, for example, arotating drum of a plasma furnace known per se for carrying out alow-temperature plasma treatment.

In a next process step 14, the process parameters and process gassesdesired for the treatment of the starting material are set. Here, inparticular, the specific combinations of the process gasses, i.e. forexample a first treatment with an inert gas plasma, preferably withhelium and/or argon, and the subsequent treatment with a reaction gasplasma, preferably with oxygen and/or nitrogen, or also the treatmentwith a plasma which is produced from a mixture of the above-mentionedgasses, are laid down. Further, the high frequencies necessary forgenerating the plasma in a vacuum and their time sequence are set. Thus,conceivable variants are ones in which a plasma treatment is carried outfirst using a relatively low frequency, for example 13.56 MHz, andsubsequently using a higher frequency, for example 2.45 GHz. Inaddition, alternating switching on of the frequencies is conceivable. Ofcourse, it is also possible to set other frequencies in any freelyselectable order for carrying out the plasma treatment. The untreatedwax is placed in motion during the plasma treatment by setting thedesired rotation rate of the rotating drum, for example, in the rangebetween 4 and 20 revolutions per minute. Also, the desired processpressure which is, for example, in the range of 0.1 mbar to 2 mbar, andmore preferably between 0.3 mbar and 1 mbar is set, During the plasmatreatment, the process pressure can be subject to fluctuations as aresult of the process. Furthermore, the treatment time for which thestarting material is treated is set. This is, for example, 5 to 800seconds, and preferably between 15 and 600 seconds. Said processparameters or process gasses can be varied among one another in anyconfiguration and are, in particular, matched to the composition of therespective particular starting material, i.e. the untreated wax, andalso to the desired use of the end product.

The plasma treatment of the starting material is then carried out in anext process step 16 using the process parameters or process conditionsset in step 14. Here, it is likewise conceivable that a change and/ormatching of the process parameters can be carried out, for example bymeans of regulation, during the plasma treatment in step 16.

For the waxes of the invention, any conceivable application requiringthe use of a wax in possible. This can be, for example, the preparationof dispersions, emulsions and solutions for coating and/or impregnatingany materials. Furthermore, use as hot melt for coating, polymeradditive, dispersant, compatibilizer for compounds, melt adhesive,auxiliary in plastics processing, surfactant, release agent, lubricantand also as constituent in the preparation of said applications, thepreparation of surface coating dispersion, the preparation of soaps, thepreparation of detergents and the preparation of sizes for glass andcarbon fibers is possible.

In a concrete example, the rotation drum of a low-temperature plasmaunit known per se is charged with, as starting material, a polyethylenewax, for example LE wax 112, in coarse powder form. As processparameter, a process pressure of 0.8 mbar is set at a rotational speedof the rotating drum of eight revolutions per minute. The power of themicrowave generator is 250 watt and that of the high-frequency injectionis likewise 250 watt. The low-temperature plasma treatment is carriedout, in the case of an argon plasma, for 15 seconds at the highfrequency and for 15 seconds at the microwave frequency, in the case ofan oxygen plasma for 60 seconds at the high frequency and 60 seconds atthe microwave frequency and in the case of a nitrogen plasma for 30seconds at the high frequency and 30 seconds at the microwave frequency.The microwave generator here produces a frequency of 2.45 GHz and thehigh-frequency injection produces a frequency of 13.56 MHz. Aftertreatment of the starting material is complete, there is obtained a waxfrom which an aqueous dispersion can be prepared at room temperature,while no aqueous dispersion can be prepared at room temperature usingthe LE wax 112 used as starting material.

I claim:
 1. A wax which has been modified by having polar groupsincorporated into a starting wax, the modified wax being prepared bysubjecting a starting wax in granulated or powdered form to a lowtemperature plasma treatment employing a frequency within the range offrom 10 kHz to 10 GHz, while maintaining during the treatment a processatmosphere enabling incorporation of polar groups into the wax.
 2. Thewax according to claim 1, wherein the polar groups are selected from thegroup consisting of carbonyl, hydroxyl, carboxyl and amino groups.
 3. Aprocess for the production of a modified wax, which comprises subjectinga starting wax in granulated or powdered form to a low temperatureplasma treatment employing a frequency in the range of from 10 kHz to 10GHz and in the presence of a process gas which enables the incorporationof polar groups into the wax.
 4. The process according to claim 3,wherein in the plasma treatment is carried out within a frequency rangeof from 13.56 MHz to 2.45 GHz.
 5. The process according to claim 3,wherein the plasma treatment is carried out using changing frequencies.6. The process according to claim 5, wherein the plasma treatment iscarried out using combinations of various changing frequencies.
 7. Theprocess according to claim 3, wherein the starting wax is selected fromthe group consisting of paraffin waxes, polyolefin waxes, and montanwaxes.
 8. The process according to claim 3, wherein the plasma treatmentis carried out in the presence of an inert gas.
 9. The process accordingto claim 3, wherein the plasma treatment is carried out in the presenceof a reaction gas.
 10. The process according to claim 3, wherein theplasma treatment is carried out successively using at least one inertgas plasma and at least one reaction gas plasma or at least one plasmaof a reaction gas mixture or in the presence of a mixture of at leastone inert gas and at least one reaction gas.
 11. The process accordingto claim 3, wherein the plasma treatment is carried out at a processpressure of from 0.1 mbar to 2 mbar.
 12. The process according to claim3, wherein the duration of the plasma treatment is from 5 s to 800 s.13. The process according to claim 3, wherein the starting wax is placedin motion during the plasma treatment.
 14. The process according toclaim 13, wherein the wax is tumbled in a rotating drum during theplasma treatment.
 15. The process according to claim 3, wherein theprocess gas is a gas selected from the group consisting of argon,helium, oxygen and nitrogen.